KHAZAIR CHECKPOINT, Iraq (UNHCR) - They left in a hurry. A farmer abandoned his crops in the field. A mother fled with her newborn, just six days old, in white swaddling clothes. Another woman managed to bring just one possession: her government ID.

Some 300,000 Iraqis, by official count, have fled fighting in northern Iraq and sought shelter in Iraq's comparatively peaceful Kurdistan region over the past week. Most ran from the upsurge in violence in Iraq's second city of Mosul.

They've found refuge with friends and relatives. Others are being hosted in mosques and disused schools. But finding adequate shelter for "the vast majority" of those who have fled Iraq's latest fighting is a "major challenge," said UNHCR's Iraq Representative Shoko Shimozawa.

The UN refugee agency and its partners in the region, including the local government, are targeting the most vulnerable families for emergency assistance, she said. But "with the sudden mass movement of people and concerns that there could be further displacement if the fighting doesn't stop, we urgently need extra funds to meet people's basic needs."

Those needs are increasing. Tayba, 48, is a widow and mother of five. She arrived at a checkpoint on the border of northern Iraq on the same day last week that Mosul fell. "There were bombs and shooting and bullets - even in the garden of our house," she recalled.

She and her children ran from their home only to watch as a neighbour was shot in the head in crossfire and died in front of them. "There was firing from different directions, we couldn't even tell where it was coming from," she said, gesturing frantically.

Eventually, Tayba and three of her five children, including an 11-year-old daughter, who lives with disability, found a car to the border. That car ran out of gas but another passerby gave her family a lift to the Khazair checkpoint, where she spoke to UNHCR. "I don't know why the situation is like this," she said. "It is very bad. In Iraq, the war is not coming to an end. It keeps on happening. I will stay here until they tell me the situation in our home is safe."

Fawzya, a mother of 10, is facing a similar plight. She fled her home in Mosul last week in the middle of the night, with only her identity card in her pocket. "My children were all crying and frightened," she said. "Some were sick. Others could barely walk. But we had to leave."

Some of the newly displaced are living in the open, in parks and built-up areas. Others are crammed into hotel rooms with several other families, though savings to pay for those rooms are running low. Children begging in the city of Erbil say they are trying to get enough money to help afford a night's rest for their families.

UNHCR and its partners, including the local government, are providing tents as well as food, kitchen sets and other emergency supplies. One transit camp has been set up at Khazair in Erbil governorate by local authorities and another is under construction at Garmawa in Duhok governorate, but has started taking people in.

"We used to have a good life," said Amal Mahmood Ismail, 44, the mother of five, not all of whom made it with her to safety. "We were not rich, nor poor. We had breakfast together every morning." She paused to wipe away tears. "My daughters are here, but my son is somewhere else. My husband is sick - and my heart is broken."

For UNHCR and its partners, working to help those like Amal who've suddenly found themselves caught up in a new chapter of Iraq's decade-old war, the challenges are obvious.